GB 2 384 379 A discloses a display system having a camera and a display for the front area of a train. The digital camera is high-resolution. Zooming of the displayed image is achieved by enlarging the digital image, as the result of which only a small portion of the image is visible.
US 2006/0171038 A1 discloses a system for zooming digital images. The system includes an image sensor, an A/D converter, an image processing unit, and a display. The sensitivity of the image converter is higher than the resolution of the display. For example, the image converter is formed by a CMOS converter having a resolution of 4096×3072 pixels, while the display has a resolution of 1024×768 pixels.
The SC100 digital camera manufactured by Olympus has an image sensor with 10.6 million pixels having a pixel pitch of 1.67 μm. The camera has a maximum refresh rate of 42 images per second at a resolution of 968×686 pixels. The refresh rate drops to 3 images per second when the highest resolution is used.
A method for refocusing is presented in the technical article by E. J. Botcherby, R. Juskaitis, M. J. Booth, T. Wilson: “An optical technique for remote focusing in microscopy” in Optics Communications 281 (2008) 880-887. This method avoids spherical aberration, and allows a large axial scan area and a high scan speed without mechanical interference between the objective lens and the sample.